Such a system is already known from European patent document No. 0 567 773. In that known switching system, the busbar disconnector and the starter disconnector are designed as a single three-position disconnector having three fixed contacts and a moving contact which needs to be implemented in the form of a rotary blade. Although economical at relatively low currents, such an organization becomes expensive to implement for nominal currents starting at 6300 A, because of the special adaptation required for the rotary blade at such a nominal current value. Such a nominal current value is typical for an alternator in a power station of the gas turbine or combined-cycle type.